This invention relates generally to the field of mobile communication and more specifically to mobile communication system that uses a NAR.
In conventional cellular GSM mobile telephony networks, subscriber data for a mobile telephone subscriber is maintained in a central data base, called the Home Location Register (“HLR”). As the number of subscribers and thus the need for calling numbers increases, the planning required for organizing the HLR, Subscriber Identity Module (“SIM”) card, and Voice Mail Service Center (“VMSC”) become considerably more complex. The added complexity is due in part to the need to form blocks of calling numbers and distribute them to the HLRs and VMSCs. The system planning is made more difficult due to special-request call numbers. Further complexity is added by the formation of blocks for Mobile Station ISDN Number (“MSISDN”) and the International Mobile Subscriber Identity (“IMSI”). Due to the system limitations of the HLR, mobile telephony networks with many subscribers typically have multiple HLRs. The determination of which HLR stores data for which subscriber is determined as a function of the calling numbers of the mobile telephone subscriber or the subscriber's IMSI. The determination of which subscriber data is on which HLR is part of the network design. Other network elements also contain subscriber-specific data including the Service Control Points (“SCP”) with integrated Service Data Function (“SDF”) and the Voice Mail Centers (“VMSC”) that provide centralized answering services.
Since GSM subscriber data is stored in the HLRs and each subscriber is identified by an MSISDN or an IMSI, the Mobile Services Switching Centers (“MSC”) and the Visitor Location Register (“VLR”) must be able to determine the subscriber's HLR based solely on an MSISDN or an IMSI. Due to capacity and administrative limits, all individual calling numbers and IMSIs cannot be stored in the MSCs routing tables. The MSISDN is used for Mobile Terminating Calls (“MTC”) and the IMSI is used for location updates. The call routing is defined by the MSC. Since an individual IMSI of an international subscriber is programmed in the SIM cards, the combination of SIM card and calling number must match when the subscriber is activated and they must be assigned to the same HLR. If this is not the case, a virtual subscriber entry is created in the HLR, which may have limited capacity available. Subscriber distribution to HLRs becomes increasingly more difficult as the number of subscribers and/or HLRs increases. The capacity of the HLRs will be further drained as additional network identification numbers are added.
Some customers request a specific calling number (telephone number”). Allocating calling numbers to specific customers complicates the configuration of the MSCs and distribution of the calling numbers to the existing HLR. When the calling number space available for activation is already set up, allocating a specific calling number to a customer is even more difficult.
HLR splits commonly occur when a new HLR is put into service. Calling number and IMSI ranges are assigned to the new HLR so that subscribers can be activated in this new HLR. Such assignments are characterized during HLR roll-out similarly to calling number allocation and numbering planning by the Voice Mail Service Center (“VMSC”). Thus, adding a new HLR requires an immense amount of planning and is highly susceptibility for errors. HLR capacity is often wasted as a result.
Similar considerations as those posed in conjunction with adding an HLR can also result for other network elements having subscriber-specific data. For example, the subscriber data for Intelligent Network (“IN”) services of a subscriber are stored in the Service Control Point (“SCP”).
The global system for mobile communications (“GSM”) standard is well known. The GSM standard § 03.02 (ETS 300.522) concerns European digital telecommunications system (Phase 2). The European Telecommunications Standard of Institutes (“ETSI”) defines a network architecture for GSM network, including digital cellular telecommunications system. The GSM standard section § 03.04 (ETS 300.524) concerns the signaling requirement relating to routing of calls to mobile subscribers in the European digital cellular telecommunications system (Phase 2). The GSM standard 09.02 (ETS 300.599) further describes the European digital cellular telecommunications system (phase 2). The Mobile Application Part (“MAP”) specification describes the ETSI returns. The GSM standard § 03.12 (ETS 300,530) describes location registration procedures on the ETSI returns in the European digital cellular telecommunications system (phase 2).